Electrical alternating-current relay



Aug. 11, 1925. 1,549,658

0. ELLEFSEN ELECTRICAL ALTERNATING CURRENT RELAY Filed Aug. 26, 1921 2 Sheets-Sheet 1 FIG l Aug. 11, 1925. 1,549,658

O. ELLEFSEN I I ELECTRICAL ALTERNATING CURRENT RELAY Filed Aug. 26, 1921' 2 Sheets-Sheet 2 Tatented l -lug. ll,

cri ics.

GLE ELLEFSIEN, O1" BURNSIDE, GLASGO'W, SCU'ILANB, ASSIG'NOR TU ELECTRIC CONTROL LIMITED, 035 BRIDGET ON, GLASS-0V], SCOTLAND.

Application filed. August 26, 192.1.

RELAY.

Serial No. 495,547.

(GRANTED UNDER THE PRGVIELIilHSi GE A T (1'? MARCH 8, 1921, 41 STAT. L, 1313.)

T0 06% whom it may concern."

Be it known that 1, @Ln ELLEFSEN, a subject of the liingot Norway, residing at Lingard, Blairbeth Road, Burnside, Glasgow, Scotland, have invented new and useful Improvements in or Connected with Electrical Alternating-Gurrent Relays, for which applications have been filed in Great Britain, May 10, 1918; France, June 25,

1920; Germany, July 1, 1920; Belgium,

June 2st, 1920, and of which the following is a specification.

This invention relates to electrical alternating current relays for use in switch control systems of the character in which the circuit, containing the relay coil, is energized by the closing of a switch actuated by means of an electro-magnet, the function of the relay being to retain separated contacts oi an auxiliary circuit (a resistance switch operating circuit, for instance), in order to prevent the auxiliary circuit from being completed until the current in the relay coil circuit has subsided to a predetermined extent when the resistance may safely be reduced.

In systems of this character, iereinatter referred to as of the character defined, the relay coil has been arranged to act upon a core (or armature) which normally tends to move outwards to complete the auxiliary circuit, but which is held in its inward position, in which the contacts of the auxiliary circuit are separated, while the switch is open, by mechanical means associated with the switch, which mechanical means in the process of closing the switch are withdrawn. Thus it will be recognized that the process of releasing the relay core is in operation while the process of closing the switch is in progress, so that outward movement of the relay core may occur before the switch is actually closed, which brings the relay coil into action for retaining the relay core in its inward position, it the closing of the switch is sufficiently slow and the movement of the relay core and parts connected there with suiiiciently rapid.

The improvements according to this invention relate to alternating current relays for use in switch control systems of the character defined, and consist in providing an initial action coil (or coils) arranged in series with the coil (or coils) of a switch electro-magnet, so that the initial action coil comes into action with the coil of the switch electro-magnet to retain separated the auxiliary circuit contacts (which previously had been held separated mechanically when the switch was open), the initial action coil exerting a force which decreases as the current diminishes inthe coil of the switch electro-magnet due to the alteration in the electro-magnetic conditions produced by the movement of the switch electro-magnet in the process of closing the switch.

An example 01" the application of this invention for the control of a three phase alternating current induction motor and slip rings will now be described.

In this case a main switch is provided comprising three contact levers which normally are maintained open by gravity or other force and closed by an electro-magnet having a coil for operating a core connected to the levers. This coil is arranged in a shuntcircuit, for instance, in shunt across the mains, and in series in this shunt circuit is the initial action coil. or" the relay. For closing this shunt circuit a pilot switch is provided. The initial action coil is arranged toact upon a member having a core. The member is also adapted to be acted upon by the main coil or coils of the relay. The main coilor coils of the relay may, for enample, be arranged as tollows:(1) In series with the rotor main circuit. (2) In parallel with a resistance or impedance in the rotor main circuit. (3) Across the slip rings. l) Between a resistance or impedance cutout switch and the permanent main circuit. (5) in series with the main stator circuit, or (6) in parallel with a resistance or impedance in the main stator circuit. V fith such arrangements, upon closing the pilot switch current passes through the coil of the switch electro-magnet and the initial action coil, the coil of the switch electromagnet operates its core to close the main switch, and the initial action coil operates its core to hold the member of the relay in its inward position and contacts of an auxiliary circuit separated, and retain it there until the main switch is closed, which causes the main coil or coils oi the relay to be en ergized and come into action to retain the member until the current in the relay coils has subsided to the extent required to release the member, the release of which permits contacts to engage and complete the auxiliary circuit which may contain the coil of a resistance cut-out switch.

In the accompanying drawings, Figure l is a diagram illustrating an application of this invention to a three phase alternating current slip ring motor.

Figure 2 is an inverted plan and Figure is a side elevation partly in section illustrating relay apparatus constructed according to this invention. 7

In Figure 1, A designates a motor, B the mains, C the main switch, D the stator leads, E the rotor mains, I main coils oi the relay, G a resistance, J the coil. of the main switch electro-magnet, K an initial action coil, H a member having cores for the main relay and initial action coils of the relay. In the diagram these cores are represented as being capable of moving together with the member I-I axially with reterence to the axes of their respective coils. L a resistance cut-out switch coil, M a resistance cut-out switch, N a contact arm moving with the main switch J, and l? a contact arm moving with the member H. The member H is acted on by a spring It tending to draw it into its switch closing position. Provision is also made, but not indicated in this diagram, whereby when the main switch C is open the member H is held in its inward position by mechanical means operating with the switch. The coil J and initial action coil K are in series in a shuntcircuit across the mains, which is closed by a pilot switch S.

The operation of this system is as "follows :-Upon closing the pilot switch ti the coils J and K are energized, whereupon the initial action coil K by acting on its core retains the member H in its inward position against the tendency of the spring It to draw it into its outward position, and the switch C is closed by the action of the coil J. Nhen the switch. C has closed, the motor circuit and the main coils F F of the relay are energized and operate to re tain the member H in its inward position. In. the process of the switch C closing the current in. the circuit containing the coils J and K decreases due to the entry of the core of the switch magnet into its coil J, with the result that the main coils F F of the relay come into action tor retaining the member II in its inward position when the energy of the initial action coil K has con siderably diminished. Subsequently, when the current in the main coils F of the relay has diminished (as the motor A speeds up) to the degree required to permit the spring R to operate, the member H is released and the arm P is brought into contact with the arm N and thereby completes an auxiliary circuit containing the coil L which then operates to close the switch M and short circuit or cut out the resistance G.

'lhe comtrimtional example shown at i 1;;111'88 'z' and S; will now be described. In

thi construction (l its'lgilzll'lfs a base upon n ch are mounted three main coils 1* and one initial action coil K of the relay. Three cores 2, arrangzd one within each oi? the coils it, are carried by a member consisting of an arm 3 mounted to turn about an axis at '-l-. A. contact 6, carried by the arm 3, is adapted to complete an auxiliary circuit containing the coil of an elcctro-magnet of a resistance cut-out switch to be actuated, I alcing contact with contact 1''. The arm acted on by a spring ii which tends nn the arr into its outward position more contact into contact with 7. In coi'u-ztructhm, T designates an arm carby the main "itch, the full lines deuoeng the position of the arm T when the main switch is closed, and the dotted lines im'licating the position when open. In the onen condition of the main switch the arm Ti operates to separate and maintain contact 6 separated trorn 7. It will be noted that the middle main coil I and the initial action coil I. of the relay are arranged to act upon the same core 2, but in other terms oi CQllStltitilOal a core or armature acted on by initial action coil is not necessarily l on by a main coil of the relay.

also act's-c.

i' or controlling the cut-out or short circuiting of successive steps of resistances, there may be n'ovided a relay apparatus for each resis ance to be cut-out, the arrangement boil 1 such that the initial act-ion coil each relay, succeeding the lirst. is or ranged each in series with the coil ol an elecirosruignct for operating a cut-out sw'tch for the preceding resistance.

claim 2- v means of an electro-magnet and n auxiliary circuit, the relay comprising a rain coil which is energized when the switch is closed, as initial at nm coil arranged in series with the coil of the electro-magnet. a movable member having cores for the main and initial action coils of the relay, auxiliary circuit contacts. and means for hold in the auxiliary circuit contacts separated mechanically when the switch is open, for the purposes iorth.

2. s s'tem of switch control comprising an alternatin current relay, :1. switch ac tuated by TIL ns oi an el ectromagnet and an auxiliary circuit, the relay comprising a main coil which is energized when the switch is closed, an initial action coil arranged in series ith the coil of the electro-magnet, a movable member having cores for the main and initial action coils of the relay, auxiliary circuit contacts, one carried by the movable member and an arm car-- ried by the switch arraneed to act upon the movable member when tne switch is open, substantially as set forth.

3. A system of switch control comprising an alternating current relay, a switch actuated by means of an electro-magnet and an auxiliary circuit, the relay comprising main coils which are energized when the switch is closed, initial action coil arranged in series with the coil of the electromagnet, a movable member having cores for the main and initial action coils of the relay, auxiliary circuit contacts, and means for holding the auxiliary circuit contacts separated mechanically when the switch is open, for the purposes set forth.

4. A system of switch control comprising an alternating current relay, a switch actuated by means of an electromagnet and an auxiliary circuit, the relay comprising main coils which are energized When the switch is closed, an initial action coil arranged in series with the coil of the electromagnet, a movable member having cores for the main and initial action coils of the relay, auxiliary circuit contacts, one carried by the movable member and an arm carried by the switch arranged to act upon the movable member when the switch is open, substantially as set forth.

' OLE ELLEFSEN. 

